Author: royger
Date: Thu Jul 19 07:39:35 2018
New Revision: 336469
URL: https://svnweb.freebsd.org/changeset/base/336469
Log:
xen: add PVHv2 entry point
The PVHv2 entry point is fairly similar to the multiboot1 one. The
kernel is started in protected mode with paging disabled. More
information about the exact BSP state can be found in the pvh.markdown
document on the Xen tree.
This entry point is going to be joined with the native entry point at
hammer_time, and in order to do so the BSP needs to be bootstrapped
into long mode with the same set of page tables as used on bare metal.
Sponsored by: Citrix Systems R&D
Modified:
head/sys/amd64/amd64/xen-locore.S
head/sys/xen/interface/elfnote.h
Modified: head/sys/amd64/amd64/xen-locore.S
==============================================================================
--- head/sys/amd64/amd64/xen-locore.S Thu Jul 19 07:30:18 2018
(r336468)
+++ head/sys/amd64/amd64/xen-locore.S Thu Jul 19 07:39:35 2018
(r336469)
@@ -42,6 +42,12 @@
#include "assym.inc"
+#define VTOP(x) ((x) - KERNBASE)
+#define ENTRY_SIZE 8 /* sizeof(uint64_t) */
+
+#define GDT_CODE 0x08
+#define GDT_DATA 0x10
+
.section __xen_guest
ELFNOTE(Xen, XEN_ELFNOTE_GUEST_OS, .asciz, "FreeBSD")
ELFNOTE(Xen, XEN_ELFNOTE_GUEST_VERSION, .asciz,
__XSTRING(__FreeBSD_version))
@@ -57,6 +63,8 @@
ELFNOTE(Xen, XEN_ELFNOTE_LOADER, .asciz, "generic")
ELFNOTE(Xen, XEN_ELFNOTE_SUSPEND_CANCEL, .long, 0)
ELFNOTE(Xen, XEN_ELFNOTE_BSD_SYMTAB, .asciz, "yes")
+ /* For PVHv2 support. */
+ ELFNOTE(Xen, XEN_ELFNOTE_PHYS32_ENTRY, .long, VTOP(xen_start32))
.text
.p2align PAGE_SHIFT, 0x90 /* Hypercall_page needs to be PAGE aligned */
@@ -64,6 +72,7 @@
NON_GPROF_ENTRY(hypercall_page)
.skip 0x1000, 0x90 /* Fill with "nop"s */
+/* Legacy PVH entry point, to be removed. */
NON_GPROF_ENTRY(xen_start)
/* Don't trust what the loader gives for rflags. */
pushq $PSL_KERNEL
@@ -85,3 +94,141 @@ NON_GPROF_ENTRY(xen_start)
/* NOTREACHED */
0: hlt
jmp 0b
+
+/* PVH entry point. */
+ .code32
+NON_GPROF_ENTRY(xen_start32)
+
+ /* Load flat GDT */
+ movl $VTOP(gdtdesc32), %eax
+ lgdt (%eax)
+ jmp $GDT_CODE, $VTOP(reload_cs)
+
+reload_cs:
+ movw $GDT_DATA, %ax
+ movw %ax, %ds
+ movw %ax, %es
+ movw %ax, %ss
+
+ movl $VTOP(bootstack), %esp
+
+ /* Don't trust what the loader gives for eflags. */
+ pushl $PSL_KERNEL
+ popfl
+
+ /*
+ * Create the page tables.
+ * The first 1GB is mapped using 2MB entries.
+ */
+ movl $0, %eax
+pgbuild:
+ cmp $(PAGE_SIZE/ENTRY_SIZE), %eax
+ jae pgbuild_done
+
+ /* PT4[i] = VTOP(&PT3[0]) | PG_V | PG_RW | PG_U */
+ movl $VTOP(PT4), %ecx
+ movl $VTOP(PT3), %edx
+ orl $(PG_V | PG_RW | PG_U), %edx
+ movl %edx, (%ecx,%eax,ENTRY_SIZE)
+
+ /* PT3[i] = VTOP(&PT2[0]) | PG_V | PG_RW | PG_U */
+ movl $VTOP(PT3), %ecx
+ movl $VTOP(PT2), %edx
+ orl $(PG_V | PG_RW | PG_U), %edx
+ movl %edx, (%ecx,%eax,ENTRY_SIZE)
+
+ /* PT2[i] = i * 2MiB | PG_V | PG_RW | PG_PS | PG_U */
+ movl $VTOP(PT2), %ecx
+ movl %eax, %edx
+ shll $PDRSHIFT, %edx
+ orl $(PG_V | PG_RW | PG_PS | PG_U), %edx
+ movl %edx, (%ecx,%eax,ENTRY_SIZE)
+
+ inc %eax
+ jmp pgbuild
+
+pgbuild_done:
+ /* Turn on EFER.LME */
+ movl $MSR_EFER, %ecx
+ rdmsr
+ orl $EFER_LME, %eax
+ wrmsr
+
+ /* Turn on PAE */
+ movl %cr4, %eax
+ orl $CR4_PAE, %eax
+ movl %eax, %cr4
+
+ /* Set %cr3 for PT4 */
+ movl $VTOP(PT4), %eax
+ movl %eax, %cr3
+
+ /* Turn on paging (implicitly sets EFER.LMA) */
+ movl %cr0, %eax
+ orl $CR0_PG, %eax
+ movl %eax, %cr0
+
+ /* Now we're in compatibility mode. Set %cs for long mode */
+ movl $VTOP(gdtdesc), %eax
+ lgdt (%eax)
+ ljmp $GDT_CODE, $VTOP(longmode)
+
+ .code64
+longmode:
+ /* We're still running V=P, jump to entry point */
+ movq $bootstack, %rsp
+ movq $start_kernel, %rax
+ pushq %rax
+ ret
+
+start_kernel:
+ /*
+ * Pass %ebx as the argument to hammer_time_xen, it contains
+ * the startup info.
+ */
+ movq %rbx, %rdi
+ call hammer_time_xen
+ movq %rax, %rsp
+ call mi_startup
+
+ /* NOTREACHED */
+0: hlt
+ jmp 0b
+
+/* Space for initial page tables */
+ .data
+ .p2align 12,0x40
+PT4:
+ .space 0x1000
+PT3:
+ .space 0x1000
+PT2:
+ .space 0x1000
+
+/* 64bit GDT */
+gdtdesc:
+ .word gdtend - gdt
+ .long VTOP(gdt) # low
+ .long 0 # high
+gdt:
+ .long 0 # null descriptor
+ .long 0
+ .long 0x00000000 # %cs
+ .long 0x00209800
+ .long 0x00000000 # %ds
+ .long 0x00008000
+gdtend:
+
+/* 32bit GDT */
+gdtdesc32:
+ .word gdt32end - gdt32
+ .long VTOP(gdt32)
+ .long 0
+gdt32:
+ .long 0 # null descriptor
+ .long 0
+ .long 0x0000ffff # %cs
+ .long 0x00cf9a00
+ .long 0x0000ffff # %ds, %es, %ss
+ .long 0x00cf9200
+gdt32end:
Modified: head/sys/xen/interface/elfnote.h
==============================================================================
--- head/sys/xen/interface/elfnote.h Thu Jul 19 07:30:18 2018
(r336468)
+++ head/sys/xen/interface/elfnote.h Thu Jul 19 07:39:35 2018
(r336469)
@@ -200,9 +200,19 @@
#define XEN_ELFNOTE_SUPPORTED_FEATURES 17
/*
+ * Physical entry point into the kernel.
+ *
+ * 32bit entry point into the kernel. When requested to launch the
+ * guest kernel in a HVM container, Xen will use this entry point to
+ * launch the guest in 32bit protected mode with paging disabled.
+ * Ignored otherwise.
+ */
+#define XEN_ELFNOTE_PHYS32_ENTRY 18
+
+/*
* The number of the highest elfnote defined.
*/
-#define XEN_ELFNOTE_MAX XEN_ELFNOTE_SUPPORTED_FEATURES
+#define XEN_ELFNOTE_MAX XEN_ELFNOTE_PHYS32_ENTRY
/*
* System information exported through crash notes.
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